CN111108278B

CN111108278B - Controller and method

Info

Publication number: CN111108278B
Application number: CN201880060386.1A
Authority: CN
Inventors: J·贝塔; G·布拉特
Original assignee: Siemens Energy Global GmbH and Co KG
Current assignee: Siemens Energy Global GmbH and Co KG
Priority date: 2017-09-18
Filing date: 2018-09-12
Publication date: 2022-12-09
Anticipated expiration: 2038-09-12
Also published as: WO2019053043A1; EP3457030A1; RU2737489C1; EP3685027B1; US20210071590A1; CN111108278A; EP3685027A1; CA3072691A1; US11261802B2; CA3072691C

Abstract

A controller (50) for a gas turbine is described. The gas turbine is arranged to supply a load L. The gas turbine comprises a fuel supply arranged to supply fuel to the combustion means at a fuel flow rate FF, wherein the fuel supply comprises a first fuel supply and a second fuel supply. The controller (50) is arranged to: one or more ratios R of one or more burner operating parameters COP at the load L to corresponding reference burner operating parameters COPR at a reference load LR are determined. The controller (50) is further arranged to: controlling the proportion P of the fuel flow rate FF supplied via the first fuel supply based at least in part on the determined one or more ratios R. A gas turbine (600) and a method of controlling a gas turbine are also described.

Description

Controller and method

Technical Field

The present invention generally relates to a controller for a gas turbine, and to a gas turbine comprising such a controller and a method of controlling such a gas turbine.

Background

An example of a typical gas turbine arrangement is shown in FIG. 1. The gas turbine comprises an air intake 10 at one end behind a compressor stage 11, in which compressor stage 11 incoming air is compressed for application to one or more combustion devices 12, which one or more combustion devices 12 are distributed circumferentially around a turbine axis 13. Fuel is introduced into the combustion device at 14 and mixed therein with a portion of the compressed air leaving the compressor stage 11. In the combustion device, the hot gases resulting from the combustion are directed to a set of turbine blades 15, in the process of which the hot gases are directed by a set of guide blades 16, and the turbine blades 15 and the shaft forming the axis 13 are thereby rotated. The turbine blades 15 in turn rotate the blades of the compressor stage 11, so that, once the gas turbine is in operation, the gas turbine itself is supplied with compressed air.

A portion of a typical combustion apparatus is shown in fig. 2A. Fig. 2B shows a cross section along the line III-III shown in fig. 2A. The combustion device is divided into four parts: a front end portion 20, a swirler portion 21, a burner pre-chamber portion 22 and a combustion volume 23. The main fuel is introduced into the swirler 21 through a duct 24 and by means of the nose portion 20, while the pilot fuel enters the burner space through a duct 25, the duct 25 having a pilot fuel nozzle 29 at its end. The main fuel flow and the pilot fuel flow originate from a fuel split valve 26, which fuel split valve 26 is supplied with a fuel supply 27, which fuel supply 27 represents the total fuel supply for the combustion device. The main fuel flow enters the swirler through a set of main fuel nozzles (or injectors) 28, from where it is directed along swirler vanes 30, in the process mixing with incoming compressed air. The fuel may be a gaseous fuel or a liquid fuel. The resulting air/fuel mixture maintains the burner flame 30. Hot air from the flame enters the combustion volume 23. A gas turbine will typically include several such combustion devices, in which case the main fuel flow profile and the pilot fuel flow profile will typically be as shown in fig. 3. Due to environmental concerns, efforts have been made to reduce the pollutant emissions of gas turbines. Potential pollutant emissions include: oxides of nitrogen (NO and NO) ₂ Commonly known as NOx), carbon monoxide (CO), unburned hydrocarbons (UHC, commonly expressed as equivalent methane), oxides of Sulfur (SO) ₂ And SO ₃ ) And Particulate Matter (PM). UHC typically includes Volatile Organic Compounds (VOCs) that contribute to the formation of ground-level atmospheric ozone in addition to compounds that do not contribute to ozone formation, such as methane and ethane. When burning natural gas, SO ₂ The amounts of UHC and PM are generally considered negligible. However, when burning natural gas and/or fuel oil in a gas turbine, NOx emissions and potential CO emissions can be important.

The amount of NOx produced depends on the combustion temperature and/or the fuel-air ratio. NOx emissions are reduced when combustion occurs at lower temperatures and/or at lower fuel to air ratios. Conventional methods for reducing NOx emissions include: wet Low Emissions (WLE), in which water injection or steam is injected to lower the fuel-air ratio, and Dry Low Emissions (DLE) and Dry Low NOx (DLN); dry Low Emissions (DLE) and Dry Low NOx (DLN) use the principle of low oxygen premixed combustion. DLE can reduce NOx emissions and CO emissions to less than 25ppmv or even less than 10ppmv, while DLN can reduce NOx emissions to less than 25ppmv.

FIG. 4A shows a graph of turbine inlet temperature (TET) as a function of load L for a typical gas turbine. For such typical gas turbines without part load emission requirements (particularly CO), the term "natural turn down" may be used, whereby for limited loads, low emissions are achieved, but no control techniques are employed to maintain a higher turn down control temperature (TCT), such as Variable Guide Vanes (VGV) or bleed to exhaust (B2E). The dashed line in FIG. 4A depicts the relationship between TCT and load L when the part load dump technique is not employed.

To achieve lower emissions at lower loads, variable Guide Vane (VGV) modulation or bleed to exhaust gas (B2E) may be used to maintain a constant turbine inlet temperature (TET). This constant temperature line is referred to as the Turndown Control Temperature (TCT) line and is shown as a solid line in fig. 4A. Typically, the pilot fuel split setting is defined based on the gas turbine TET. This means that: as the load L decreases along TCT, the pilot split remains constant throughout the load range. Thus, there is limited control over combustion performance in terms of combustion dynamics, for example, in terms of flame stability (also referred to as combustion stability) and/or emissions (e.g., at different loads on the TCT line).

FIG. 4B illustrates a graph of turbine inlet temperature (TET) and pilot split as a function of load L for a typical gas turbine.

Specifically, FIG. 4B shows pilot split behavior along the TCT line. Known pilot fuel control algorithms typically maintain a constant predefined pilot split value along a constant TCT line as the load decreases. This may limit control of combustion parameters such as flame stability and/or NOx emissions at various load conditions. Known pilot fuel control algorithms rely on inputs from low frequency dynamics and on combustor tip measurements and may be mapped against TET such that control of known pilot fuel control algorithms is somewhat limited when TET is constant.

However, at lower temperatures (e.g., TET) and/or at lower fuel to air ratios, conventional methods of reducing NOx emissions result in a decrease in the thermodynamic efficiency of the gas turbine. This is contrary to the typical goal of improving thermodynamic efficiency. Further, these conventional methods of reducing NOx emissions typically involve operating the gas turbine at full load. In addition, known pilot fuel control algorithms for low loads provide limited control over fuel dynamics (e.g., flame stability and/or emissions). In addition, flame stability and/or emissions may be affected by complex interactions between environmental and operating conditions, as well as gas turbine specific factors (such as life and pollution).

Accordingly, there is a need for improved control of gas turbines to improve flame stability and/or emissions.

Disclosure of Invention

One object of the invention is in particular: a controller for a gas turbine including such a controller and a method of controlling such a gas turbine are provided that improve flame stability and/or emissions, for example at lower temperatures and/or lower loads.

According to a first aspect, there is provided a controller for a gas turbine arranged to supply a load L, the gas turbine comprising a total fuel supply arranged to supply fuel to a combustion device at a fuel flow rate FF, wherein the fuel supply comprises a first fuel supply and a second fuel supply, wherein the controller is arranged to:

determining one or more ratios R of one or more burner operating parameters COP at a load L and a corresponding reference burner operating parameter coprr at a reference load LR, respectively; and controlling the proportion P of the fuel flow rate FF supplied via the first fuel supply arrangement based at least in part on the determined one or more ratios R.

According to a second aspect, there is provided a gas turbine arranged to supply a load L, the gas turbine comprising a fuel supply arranged to supply fuel to a combustion device at a fuel flow rate FF, wherein the fuel supply comprises a first fuel supply and a second fuel supply, wherein the gas turbine comprises a controller arranged to:

determining one or more ratios R of one or more burner operating parameters COP at a load L and a corresponding reference burner operating parameter coprr at a reference load LR, respectively; and is

Controlling the proportion P of the fuel flow rate FF supplied via the first fuel supply based at least in part on the determined one or more ratios R.

According to a third aspect, there is provided a method of controlling a gas turbine arranged to supply a load L, the gas turbine comprising a total fuel supply arranged to supply fuel to a combustion device at a fuel flow rate FF, wherein the fuel supply comprises a first fuel supply and a second fuel supply, the method comprising:

determining one or more ratios R of one or more burner operating parameters COP at a load L and a corresponding reference burner operating parameter coprr at a reference load LR, respectively; and

controlling a proportion P of a fuel flow rate FF supplied via the first fuel supply based at least in part on the determined one or more ratios R;

thereby, flame stability and/or emissions are improved.

Preferably, the proportion P of the fuel flow rate FF supplied via the first fuel supply means is controlled at least partly on the basis of the determined ratio or ratios R, this control being without any other condition-based (internal or external) correction factor. This means that the invention is advantageous because it is relatively simple to calculate the fuel split using a predefined value of the pilot fuel split, which is based on the conditionally calculated COP, instead of time tracking and post-processing other input parameters. The invention is simple and therefore computationally less demanding, so the response is faster.

According to a fourth aspect, there is provided a tangible, non-transitory computer-readable storage medium having instructions recorded thereon, which, when executed by a controller for a gas turbine arranged to supply a load L, the gas turbine comprising a fuel supply arranged to supply fuel to a combustion arrangement at a fuel flow rate FF, the fuel supply comprising a first fuel supply and a second fuel supply, cause the controller to perform a method of controlling a gas turbine according to the third aspect.

According to a fifth aspect, a controller for a gas turbine arranged to supply a load L is provided, the gas turbine comprising a fuel supply arranged to supply fuel to a combustion device at a fuel flow rate FF, wherein the fuel supply comprises a first fuel supply and a second fuel supply, wherein the controller is arranged to control a proportion P of the fuel flow rate FF supplied via the first fuel supply at least partly on the basis of the fuel flow rate FF.

According to a sixth aspect, there is provided a gas turbine arranged to supply a load L, the gas turbine comprising a fuel supply arranged to supply fuel to a combustion device at a fuel flow rate FF, wherein the fuel supply comprises a first fuel supply and a second fuel supply, wherein the gas turbine comprises a controller arranged to: the proportion P of the fuel flow rate FF supplied via the first fuel supply is controlled based at least in part on the fuel flow rate FF.

According to a seventh aspect, there is provided a method of controlling a gas turbine, the gas turbine being arranged to supply a load L, the gas turbine comprising a fuel supply arranged to supply fuel to a combustion device at a fuel flow rate FF, wherein the fuel supply comprises a first fuel supply and a second fuel supply, the method comprising:

controlling a proportion P of a fuel flow rate FF supplied via a first fuel supply based at least in part on the fuel flow rate FF;

thereby, the metal temperature and/or emissions are improved.

According to an eighth aspect, there is provided a tangible, non-transitory, computer-readable storage medium having instructions recorded thereon, which, when executed by a controller for a gas turbine arranged to supply a load, the gas turbine comprising a fuel supply arranged to supply fuel to a combustion apparatus at a fuel flow rate FF, wherein the fuel supply comprises a first fuel supply and a second fuel supply, cause the controller to perform a method of controlling the gas turbine according to the seventh and/or third aspect.

Detailed description of the invention

According to the present invention, there is provided a controller for a gas turbine as set out in the appended claims. The invention also provides a gas turbine, a method of controlling a gas turbine, and a tangible, non-transitory computer-readable storage medium. Further features of the invention will be apparent from the dependent claims and the subsequent description.

Throughout this specification, the term "comprising" or "comprises" means including the specified component(s), but not excluding the presence of other components. The term "consisting essentially of or" consisting essentially of means including the specified components, but excluding other components in addition to the following materials and components: materials present as impurities, inevitable materials present as a result of processes used to provide the components, and components (such as colorants and the like) added for purposes other than achieving the technical effects of the present invention.

The term "consisting of" or "consisting of" is intended to include the specified components, but exclude other components.

The use of the terms "comprising" or "including," depending on the context, may also be understood to include the meaning of "consisting essentially of or" consisting essentially of, and likewise may also be understood to include the meaning of "consisting of or" consisting of, "as appropriate.

The optional features set out herein may be used alone or in combination with one another where appropriate, and in particular in combinations as set out in the appended claims. Optional features for each aspect or exemplary embodiment of the invention (as set out herein) are also applicable to all other aspects or exemplary embodiments of the invention, where appropriate. In other words, a person skilled in the art who has read this description shall consider optional features for each aspect or exemplary embodiment of the invention as being interchangeable and combinable between different aspects and exemplary embodiments.

According to a first aspect, a controller for a gas turbine arranged to supply a load L, the gas turbine comprising a total fuel supply arranged to supply fuel to a combustion device at a fuel flow rate FF, wherein the total fuel supply comprises a first fuel supply and a second fuel supply, wherein the controller is arranged to:

determining one or more ratios R of one or more burner operating parameters COP at a load L and a corresponding reference burner operating parameter coprr at a reference load LR, respectively; and is provided with

Controlling the proportion P of the fuel flow rate FF supplied via the first fuel supply arrangement based at least in part on the determined one or more ratios R. By controlling the proportion P (i.e., the split) of the fuel flow rate FF supplied via the first fuel supply (e.g., the pilot fuel supply), the proportion P may be varied along a Turndown Control Temperature (TCT) line (e.g., a substantially constant TCT line) as the load L, which is based at least in part on the determined one or more ratios R, varies, for example, beginning at a full load L that may be provided by the gas turbine. In this manner, control of the gas turbine may be improved to improve flame stability and/or emissions, for example, as load L changes.

For example, controlling the proportion P in this manner may be applied as a modification to a conventional pilot fuel control algorithm to calculate a pilot split offset for each load L based at least in part on the determined one or more ratios R and apply the pilot split offset to a conventional pilot split map and/or envelope the map.

In this manner, along a substantially constant TCT line, control of the pilot split (i.e., ratio P) at each load may provide improved (e.g., more accurate) initial conditions to achieve improved combustion performance in terms of flame stability and/or emissions. By improving flame stability, the reliability of the gas turbine can be improved. By improving emissions (e.g., reducing NOx emissions), the environmental impact may be improved.

For example, as the load L decreases, the conventional pilot split may be a predefined constant pilot split value along a constant TCT line.

Conversely, as the load L decreases, the proportion P (i.e., the pilot split according to the present disclosure) is non-constant along the constant TCT line, which is controlled based at least in part on the determined proportion or proportions R, as described above.

Specifically, the ratio P increases linearly, for example, as the load L increases along the TCT line. At the low end of the constant TCT line, the ratio P will be less than the conventional pilot split, while at the high end of the constant TCT line, the ratio P will tend toward and/or be equal to the conventional pilot split. At load L below the low end of the constant TCT line, the ratio P will increase as TET decreases, less than the conventional pilot split, but will tend toward the conventional pilot split as load L decreases. At a constant load L above the high end of the TCT line, the proportion P will decrease as TET increases until full load L, substantially equal to the conventional pilot split value. That is, for a given load L, the proportion P will be at most the conventional pilot split value, and for an intermediate load L (e.g., in the range of about 10% to 60% of full load L), the proportion P will be less than the conventional pilot split value.

The gas turbine may be as described with reference to fig. 1 to 3.

In one example, the combustion device comprises and/or is a can combustion device, an annular combustion device, or a tubular combustion device. In one example, a gas turbine includes a plurality of combustion devices, such as such combustion devices. In one example, the first fuel supply comprises a pilot fuel supply, and/or the first fuel supply is a pilot fuel supply. In one example, the first fuel supply is a single pilot fuel supply. In one example, the second fuel supply comprises a primary fuel supply, and/or the second fuel supply is a primary fuel supply. In one example, the gas turbine comprises a plurality of combustion devices, the first fuel supply device comprises a plurality of pilot fuel supply devices, for example a corresponding pilot fuel supply device and/or a respective pilot fuel supply device, and the second fuel supply device comprises a plurality of main fuel supply devices, for example a corresponding main fuel supply device and/or a respective main fuel supply device. In other words, each combustion device may include a pilot fuel nozzle and a main fuel nozzle associated with the first and second fuel supplies, respectively. In one example, the fuel is a gaseous fuel, such as natural gas. In one example, the fuel is a liquid fuel, such as fuel oil.

In one example, the reference load LR is the full load that may be supplied by the gas turbine (i.e., 100% load L).

In one example, the burner operating parameter COP is one burner operating parameter COP selected from the group consisting of a combustion intensity of the burner CI, an equivalence ratio of the burner ER, and a burner inlet function of the burner CIF.

The present inventors have determined that one or more of these combustion device operating parameters COP may be particularly beneficial in improving flame stability and/or emissions (e.g., NOx emissions).

In one example, the combustion intensity CI is determined based at least in part on a heat input HI for the gas turbine, a compressor outlet pressure CEP of the gas turbine, and/or a combustion device volume CV of the combustion device, and the controller is arranged to determine the combustion intensity CI;

determining a first ratio R1 of the combustion intensity CI at the load L to the reference combustion intensity CIR at the reference load LR; and is

The proportion P of the fuel flow rate FF supplied via the first fuel supply is controlled based at least in part on the determined first proportion R1.

In one example, the reference load LR is a full load that may be supplied by the gas turbine, and the reference firing strength CIR at the reference load LR is a firing strength CIR at full load that may be supplied by the gas turbine.

In one example, the combustion intensity CI is determined by CI = HI/(CEP × CV), and the controller is arranged to determine the heat input HI, the compressor outlet pressure CEP and/or the combustion device volume CV.

Based on the fuel flow rate FF, the heating value of the fuel, and the specific gravity of the fuel, the heat input HI may be derived.

The compressor exit pressure CEP may be derived based on a gas turbine (engine) pressure ratio, and/or the compressor exit pressure CEP may be measured.

The combustion device volume CV may be measured or determined based on geometric measurements of the combustion system, such as the prechamber, can, and conduit.

In more detail, the combustion intensity CI may be determined by the following equation 1:

in one example, the gas turbine includes a plurality of combustion devices, and the combustion device volume CV is a total combustion device volume CV for the plurality of combustion devices. In one example, the combustion device volume is predetermined, for example by measurement, and the controller is arranged to store the combustion device volume CV.

In one example, the gas turbine includes one or more sensors arranged to sense the heat input HI and/or the compressor outlet pressure CEP, and the controller is arranged to obtain the sensed heat input HI and/or the compressor outlet pressure CEP from the one or more sensors.

In one example, the equivalence ratio ER (also referred to as Φ) is determined based at least in part on a fuel flow rate FF for the combustion device, an air flow rate FA for the combustion device, and/or a stoichiometric fuel-air ratio SFAR, and wherein the controller is arranged to:

determining an equivalence ratio ER;

determining a second ratio R2 of the equivalence ratio ER at the load L to the reference equivalence ratio ERR at the reference load LR; and is

Controlling the proportion P of the fuel flow rate FF supplied via the first fuel supply arrangement based at least in part on the determined second ratio R2.

In one example, the equivalence ratio ER is determined by ER = (FF/FA)/SFAR, and wherein the controller is arranged to determine the fuel flow rate FF, the air flow rate FA, and/or the stoichiometric fuel-air ratio SFAR.

For example, the fuel flow rate FF may be determined (e.g., measured) by using a flow meter.

The air flow rate FA may be determined (e.g., calculated) based on the compressor speed and the engine pressure ratio.

The stoichiometric fuel-air ratio SFAR may be determined (e.g., calculated) to be a value specific to a certain fuel component, and may be a theoretical value that suggests that the reaction between the carbon component and the oxygen component has been completed, and that no excess of either the carbon component or the oxygen component has occurred to completely consume both components. If more oxygen is present in the mixture, the mixture is referred to as a low oxygen mixture. This is typical for gas turbines, for which reference is usually made to low oxygen premixing systems. However, when there is an excess of fuel, then as an alternative, the oxygen enrichment system is referenced, as is also referenced for the gas turbine, but not so frequently.

In more detail, the equivalence ratio ER can be determined by the following equation 2:

wherein

In one example, the gas turbine comprises one or more sensors arranged to sense a fuel flow rate FF and/or an air flow rate FA, and the controller is arranged to obtain the sensed fuel flow rate FF and/or air flow rate FA from the one or more sensors.

In one example, the combustion apparatus inlet function CIF is determined based at least in part on an air flow rate FA for the combustion apparatus, a compressor outlet temperature CET of the gas turbine and/or a compressor outlet pressure CEP of the gas turbine, and the controller is arranged to:

determining a combustion device inlet function CIF;

determining a third ratio R3 of the burner inlet function CIF at the load L to the reference burner inlet function CIFR at the reference load LR; and is

Controlling the proportion P of the fuel flow rate FF supplied via the first fuel supply arrangement based at least in part on the determined third ratio R3.

In one example, the combustion apparatus inlet function CIF is determined by CIF = (FA × √ CET)/CEP, and the controller is arranged to determine the air flow rate FA, the compressor outlet temperature CET, and/or the compressor outlet pressure CEP.

Based on the compressor speed and the engine (i.e., gas turbine) pressure ratio, an air flow rate FA may be determined (e.g., calculated).

The compressor outlet temperature CET may be determined (e.g., measured) by a thermocouple and/or may be derived based on an engine (i.e., gas turbine) pressure ratio.

The compressor outlet pressure CEP may be determined (e.g., derived) based on the engine pressure ratio, and/or the compressor outlet pressure CEP may be measured.

In more detail, the compressor inlet pressure CIF may be determined by equation 3 as follows:

in one example, the gas turbine includes one or more sensors arranged to sense an air flow rate FA, a compressor outlet temperature CET and/or a compressor outlet pressure CEP, and the controller is arranged to obtain the sensed air flow rate FA, compressor outlet temperature CET and/or compressor outlet pressure CEP from the one or more sensors.

In one example, the controller is arranged to:

determining an exhaust flow rate FB; and is

The proportion P of the flow rate FF of fuel supplied via the first fuel supply is controlled based at least in part on the determined bleed flow rate FB.

In one example, the gas turbine includes one or more sensors arranged to sense the bleed air flow rate FB, and the controller is arranged to obtain the sensed bleed air flow rate FB from the one or more sensors.

In one example, the bleed flow rate FB is an air mass flow rate for the exhaust and/or intake of the gas turbine.

In one example, the gas turbine comprises one or more sensors arranged to sense an air mass flow rate for exhaust and/or intake air of the gas turbine, and the controller is arranged to: from the one or more sensors, a sensed mass airflow rate of air to the exhaust and/or intake of the gas turbine is obtained.

In one example, the load L and/or the fuel flow rate FF and/or the turbine inlet temperature TET are substantially constant.

In one example, the gas turbine comprises one or more sensors arranged to sense the load L and/or the fuel flow rate FF and/or the turbine inlet temperature TET, and the controller is arranged to: from the one or more sensors, the sensed load L and/or fuel flow rate FF and/or turbine inlet temperature TET are obtained.

In one example, the controller comprises a memory and a processor, wherein the memory comprises instructions that, when executed by the processor, cause the controller to perform a method of controlling a gas turbine as described herein (e.g. as described above and/or according to the third aspect). In other words, for example, according to instructions executed by the processor, the controller may be arranged to: determining one or more ratios R of the one or more combustion device operating parameters COP at the load L and the respective reference combustion device operating parameter COPR at the reference load LR, respectively, the controller may be further arranged to: the combustion device operating parameter COP is determined as described above, and/or the proportion P of the fuel flow rate FF supplied via the first fuel supply device is controlled based at least in part on the determined one or more ratios R. In one example, the controller comprises a communication unit arranged to communicate with one or more sensors as described above. In one example, the controller comprises a storage device arranged to store the following parameters: the one or more ratios R of the one or more burner operating parameters COP, respectively, at the load L, the corresponding reference burner operating parameter COPR at the reference load LR, and/or the determined burner operating parameter COP, as described above.

According to a second aspect, there is provided a gas turbine arranged to supply a load L, the gas turbine comprising, the total fuel supply arranged to supply fuel to a combustion device at a fuel flow rate FF, wherein the total fuel supply comprises a first fuel supply and a second fuel supply, wherein the gas turbine comprises a controller arranged to:

Controlling the proportion P of the fuel flow rate FF supplied via the first fuel supply arrangement based at least in part on the determined one or more ratios R.

The gas turbine, the load L, the fuel supply, the fuel flow rate FF, the combustion device, the first fuel supply, the second fuel supply, the controller, the ratio R, the combustion device operating parameter COP, the reference combustion device operating parameter COPR, the reference load LR, and/or the proportion P may be described with reference to the first aspect.

According to a third aspect, there is provided a method of controlling a gas turbine arranged to supply a load L, the gas turbine comprising a total fuel supply arranged to supply fuel to a combustion device at a fuel flow rate FF, wherein the total fuel supply comprises a first fuel supply and a second fuel supply, the method comprising:

thereby, flame stability and/or emissions are improved. The gas turbine, the load L, the fuel supply, the fuel flow rate FF, the combustion device, the first fuel supply, the second fuel supply, the controller, the ratio R, the combustion device operating parameter COP, the reference combustion device operating parameter COPR, the reference load LR and/or the proportion P may be described with reference to the first aspect and/or the second aspect. For example, the emissions may be NOx emissions.

In one example, the combustion intensity CI is determined based at least in part on a heat input HI to the gas turbine, a compressor outlet pressure CEP of the gas turbine, and/or a combustion device volume CV of the combustion device, and wherein the method comprises:

determining combustion intensity CI; determining a first ratio R1 of the combustion intensity CI at the load L to the reference combustion intensity CIR at the reference load LR; and

In one example, the combustion intensity CI is determined by CI = HI/(CEP × CV), and wherein the method comprises: the heat input HI, the compressor outlet pressure CEP and/or the combustion device volume CV are determined.

In one example, the equivalence ratio ER is determined based at least in part on a fuel flow rate FF for the combustion device, an air flow rate FA for the combustion device, and/or a stoichiometric fuel-air ratio SFAR, and wherein the method comprises:

determining an equivalence ratio ER; determining a second ratio R2 of the equivalence ratio ER at the load L to the reference equivalence ratio ERR at the reference load LR; and

the proportion P of the fuel flow rate FF supplied via the first fuel supply arrangement is controlled based at least in part on the determined second ratio R2.

In one example, the equivalence ratio ER is determined by ER = (FF/FA)/SFAR, and wherein the method comprises: the fuel flow rate FF, the air flow rate FA, and/or the stoichiometric fuel-to-air ratio SFAR are determined.

In one example, the combustion device inlet function CIF is determined based at least in part on an air flow rate FA for the combustion device, a compressor outlet temperature CET of the gas turbine, and/or a compressor outlet pressure CEP of the gas turbine, and wherein the method comprises:

determining a combustion device inlet function CIF; determining a third ratio R3 of the burner inlet function CIF at the load L to the reference burner inlet function CIFR at the reference load LR; and

the proportion P of the fuel flow rate FF supplied via the first fuel supply arrangement is controlled based at least in part on the determined third ratio R3.

In one example, the combustion device inlet function CIF is determined by CIF = (FA × √ CET)/CEP, and wherein the method comprises: an air flow rate FA, a compressor outlet temperature CET and/or a compressor outlet pressure CEP are determined.

In one example, a method comprises:

determining an exhaust flow rate FB; and

the proportion P of the fuel flow rate FF supplied via the first fuel supply is controlled based at least in part on the determined purge flow rate FB. In one example, the load L and/or the fuel flow rate FF and/or the turbine inlet temperature TET are substantially constant.

In one example, the reference load LR is the full load that may be supplied by the gas turbine.

In one example, the first fuel supply is a pilot fuel supply.

According to a fourth aspect, there is provided a tangible, non-transitory, computer-readable storage medium having instructions recorded thereon, which, when executed by a controller for a gas turbine arranged to supply a load L, cause the controller to perform a method of controlling the gas turbine according to the third aspect, the gas turbine comprising a total fuel supply arranged to supply fuel to a combustion device at a fuel flow rate FF, wherein the total fuel supply comprises a first fuel supply and a second fuel supply.

According to a fifth aspect, there is provided a controller for a gas turbine arranged to supply a load L, the gas turbine comprising a total fuel supply arranged to supply fuel to a combustion device at a fuel flow rate FF, wherein the total fuel supply comprises a first fuel supply and a second fuel supply, wherein the controller is arranged to: the proportion P of the fuel flow rate FF supplied via the first fuel supply is controlled based at least in part on the fuel flow rate FF.

By controlling the proportion P (i.e. the split) of the fuel flow rate FF supplied via the first fuel supply arrangement, based at least in part on the fuel flow rate FF, for example as the load L varies, control of the gas turbine may be improved to improve metal temperatures and/or emissions. As described below, this improvement is especially observed at high loads (e.g., > 90%) and/or higher temperatures.

For example, controlling the ratio P in this manner can be applied as a modification to a conventional pilot fuel control algorithm to calculate a pilot split offset for each load L based at least in part on the fuel flow rate FF and to apply the pilot split offset to a conventional pilot split map and/or to envelope the map.

By improving the metal temperature, the reliability of the gas turbine can be improved. By improving emissions (e.g., reducing NOx emissions), the environmental impact may be improved.

The inventors have determined that: environmental changes can have a large impact on NOx emissions and/or metal temperatures in the ignition zone where the fuel is sufficiently burned for combustion stability. That is, NOx emissions may be a function of TFIRE, which depends on air and fuel properties, such as temperature, pressure, mass flow, and the like. NOx emissions are also dependent on the pilot fuel percentage. It is desirable to balance the pilot fuel percentages well because lower pilot fuels result in less flame stability, while higher pilot fuels result in higher NOx emissions.

Conventional control methods for gas turbines, which do not take into account all of these factors, are typically based on pilot percentage (percentage of total fuel) and, as previously mentioned, are used to keep the flame stable.

The inventors have determined that: NOx emissions can be a strong function of the percentage of ignition using gaseous and/or liquid fuels. As discussed above, as the fuel flow rate increases at relatively cooler temperatures, the pilot fuel flow rate into the main combustion zone also typically increases. Further, NOx emissions may change due to volumetric heat release and/or volumetric heat generation. For example, at relatively cooler temperatures, if there is a large pilot fuel flow rate (at the same pilot split percentage) in the stability region of the combustion device (which is typically the vortex core region), the heat release will be relatively high. Therefore, the percentage pilot split according to the combustor exit temperature TX or the turbine inlet temperature T1 does not take into account NOx emissions and/or metal temperatures.

The controller may also be arranged as described with reference to the first aspect. Advantageously, as previously mentioned, the fifth aspect may improve metal temperature and/or emissions at higher loads L and/or temperatures, while the first aspect may improve flame stability and/or emissions at moderate loads L, thereby providing a synergistic advantage.

In one example, a controller for a gas turbine is provided, the gas turbine being arranged to supply a load L, the gas turbine comprising a total fuel supply arranged to supply fuel to a combustion device at a fuel flow rate FF, wherein the total fuel supply comprises a first fuel supply and a second fuel supply, wherein the controller is arranged to:

determining one or more ratios R of one or more combustion device operating parameters COP at a load L and a corresponding reference combustion device operating parameter COPR at a reference load LR, respectively; and is

The gas turbine may be as described with reference to fig. 1 to 3.

In one example, the combustion device comprises and/or is a can combustion device, an annular combustion device, or a tubular combustion device. In one example, a gas turbine includes a plurality of combustion devices, such as such combustion devices. In one example, the first fuel supply comprises a pilot fuel supply, and/or the first fuel supply is a pilot fuel supply. In one example, the first fuel supply is a single pilot fuel supply. In one example, the second fuel supply comprises a primary fuel supply, and/or the second fuel supply is a primary fuel supply. In one example, the gas turbine comprises a plurality of combustion devices, the first fuel supply device comprises a plurality of pilot fuel supply devices, for example a corresponding pilot fuel supply device and/or a respective pilot fuel supply device, and the second fuel supply device comprises a plurality of main fuel supply devices, for example a corresponding main fuel supply device and/or a respective main fuel supply device. In other words, each combustion device may include a pilot fuel nozzle and a main fuel nozzle associated with the first and second fuel supplies, respectively. In one example, the fuel is a gaseous fuel, such as natural gas. In one example, the fuel is a liquid fuel, such as fuel oil. For gaseous fuels, instead of a pilot pressure drop as described herein, the pressure ratio across the pilot fuel nozzle may be more important. Generally, the pressure ratio should be such that there is no reverse flow and/or large burner-to-burner variation.

It should be understood that the fuel flow rate FF is the total fuel flow rate FF. That is, the fuel flow rate FF includes fuel supplied to the combustion device via the first fuel supply device and the second fuel supply device. For example, if the gas turbine includes a plurality of combustion devices, the fuel flow rate FF includes fuel supplied to the plurality of combustion devices via a first fuel supply and a second fuel supply. In one example, the fuel flow rate FF is determined by the load L. That is, if the load L changes, the fuel flow rate FF will change accordingly. In one example, the gas turbine comprises one or more sensors arranged to sense (e.g. measure) the fuel flow rate FF and/or the load L, and the controller is arranged to obtain the measured fuel flow rate FF and/or the load L from the one or more sensors. In one example, the proportion P of the fuel flow rate FF supplied via the first fuel supply is controlled based at least in part on the reference fuel flow rate FFR.

In one example, the reference fuel flow rate FFR is at a first predetermined temperature T1 (preferably, the first predetermined temperature T1 is an intake air temperature of 323K of the gas turbine) and/or a first predetermined load L1 (preferably, the first predetermined load L1 is 100%).

In one example, the controller is arranged to: the proportion P of the fuel flow rate FF supplied via the first fuel supply arrangement is controlled at least partly on the basis of a reference proportion PR of the fuel flow rate FF supplied via the first supply arrangement.

In one example, the controller is arranged to: controlling the proportion P of the fuel flow rate FF supplied via the first fuel supply based at least in part on a reference proportion split PRS of the fuel flow rate FF supplied via the first supply.

Additionally and/or alternatively, the proportion P of the fuel flow rate FF supplied via the first fuel supply may be described by equation 1 below:

wherein

Metric constant SC = reference fuel flow rate FFR × reference proportional split PRS

In one example, the reference proportional diversion PRS is at a first predetermined temperature T1 (preferably, the first predetermined temperature T1 is 323K) and/or a first predetermined load L1 (preferably, the first predetermined load L1 is 100%).

In one example, the reference proportional split PRS is a pilot percentage as a function of the turbine inlet temperature T1.

In one example, the reference proportional diversion PRS is based at least in part on a minimum fuel flow rate below which a liquid spray cone from a total fuel supply nozzle (e.g., a first fuel supply nozzle) collapses.

In one example, the reference proportional split PRS is based at least in part on a minimum fuel flow rate below which no positive and/or net flow enters the combustion device via the main fuel supply nozzle (e.g., the first fuel supply nozzle).

In this way, for example, the proportion P of the fuel flow rate FF supplied via the first fuel supply arrangement, based at least in part on the fuel flow rate FF, takes into account the following physical properties: i.e., liquid fuel spray pressure drop and/or gaseous fuel pressure ratio. For example, if the pressure drop is too low, the variation between combustion devices may be significant, with different combustion zones having different fuel flow rates, making it difficult to control the gas turbine in such weak fuel flows. For example, for a liquid spray pressure drop from a pressure swirl jet or nozzle, the minimum required pressure drop may be 0.5 bar. For gaseous fuels, the minimum desired pressure ratio may be a pressure drop of 1.005 or a pressure drop of 0.5%.

In one example, the reference proportion PR of the fuel flow rate FF supplied via the first fuel supply means is at a second predetermined temperature T2 (preferably, the second predetermined temperature T2 is 323K) and/or a second predetermined load L2 (preferably, the second predetermined load L2 is 100%).

In one example, the proportion P of the fuel flow rate FF supplied via the first fuel supply is determined by P = (FFR × PR)/FF.

In one example, the reference fuel flow rate FFR is at a first predetermined temperature T1 and/or a first predetermined load L1, and/or the reference proportion PR is at a second predetermined temperature T2 and/or a second predetermined load L2.

In one example, the first predetermined temperature T1 and the second predetermined temperature T2 are the same (i.e., equal). In one example, the first and second predetermined loads L1 and L2 are the same (i.e., equal).

In one example, the controller is arranged to: the fuel flow rate FF is controlled based at least in part on the ambient temperature TA.

In one example, the gas turbine includes one or more sensors arranged to sense (e.g., measure) an ambient temperature TA, and the controller is arranged to obtain the measured ambient temperature TA from the one or more sensors.

In one example, if the combustion apparatus outlet temperature TX is greater than a third predetermined temperature T3, and/or if the turbine inlet temperature T1 is greater than a fourth predetermined temperature T4, the controller is arranged to: the proportion P of the fuel flow rate F supplied via the first fuel supply is controlled based at least in part on the fuel flow rate FF.

In one example, the gas turbine comprises one or more sensors arranged to sense (e.g. measure) the combustor exit temperature TX and/or the turbine inlet temperature T1, and the controller is arranged to obtain the measured combustor exit temperature TX and/or the measured turbine inlet temperature from the one or more sensors.

In one example, the third predetermined temperature T3 is in a range from about 1400K to 1900K, preferably the third predetermined temperature T3 is in a range from about 1500K to 1700K, and more preferably the third predetermined temperature T3 is in a range from about 1550K to 1650K.

In one example, the fourth predetermined temperature T4 is in a range from about 1400K to 1900K, preferably the fourth predetermined temperature T4 is in a range from about 1500K to 1700K, and more preferably the fourth predetermined temperature T4 is in a range from about 1550K to 1650K.

The fourth predetermined temperature T4 may depend on the specific design of the combustion apparatus.

In this way, the proportion P of the fuel flow rate FF supplied via the first fuel supply is controlled based at least in part on the fuel flow rate FF when thermal NOx emissions dominate, and/or when metal tip temperature becomes a consideration. The fuel flow rate FF supplied via the first fuel supply means is at least a minimum value at temperatures above T3 and/or T4, so that NOx emissions may be reduced in the ambient temperature range, and/or the metal temperature in the vicinity of the ignition zone may be reduced, thereby improving reliability, and/or resulting in longer component life.

The minimum required pressure drop for a reasonable spray is assumed to be at an ambient temperature of 50 ℃ and 100% load L. Below this fuel flow rate FF, there may be relatively high combustor-to-combustor variation. According to the control provided by the fifth aspect, the pilot split flow map can be changed while maintaining a reasonable pressure drop.

According to the control provided by the fifth aspect, the pilot split map may be changed based on the turbine inlet temperature T1 while ensuring the ambient temperature of 50 ℃, and the load L of 100% is the worst condition or the limit condition under which the scaling factor is calculated. In this way, the control of the gas turbine can be easily implemented.

According to the control provided by the fifth aspect, at least differences in NOx emissions between field testing and actual operating conditions can be reduced when installed on site (e.g. on site, at relatively cold ambient temperatures and/or 100% load).

In one example, if the combustion apparatus outlet temperature TX is at most the third predetermined temperature T3, the controller is arranged to control the proportion P of the fuel flow rate FF supplied via the first fuel supply apparatus to be constant.

In one example, the controller comprises a memory and a processor, wherein the memory comprises instructions that, when executed by the processor, cause the controller to perform a method of controlling a gas turbine as described herein (e.g. as described above and/or according to the third aspect). In one example, the controller comprises a communication unit arranged to communicate with one or more sensors as described above. In one example, the controller comprises a storage device arranged to store one or more predetermined loads (e.g. a first predetermined load L1) and/or predetermined temperatures (e.g. a first predetermined temperature T1, a second predetermined temperature T2, a third predetermined temperature T3 and/or a fourth predetermined temperature T4) as described above.

According to a sixth aspect, there is provided a gas turbine arranged to supply a load L, the gas turbine comprising a total fuel supply arranged to supply fuel to a combustion device at a fuel flow rate FF, wherein the total fuel supply comprises a first fuel supply and a second fuel supply, wherein the gas turbine comprises a controller arranged to: the proportion P of the fuel flow rate FF supplied via the first fuel supply is controlled based at least in part on the fuel flow rate FF.

The gas turbine, the load L, the fuel supply, the fuel flow rate FF, the combustion device, the first fuel supply, the second fuel supply, the controller and/or the proportion P may be described with reference to the fifth aspect and/or the first aspect.

According to a seventh aspect, there is provided a method of controlling a gas turbine arranged to supply a load L, the gas turbine comprising a total fuel supply arranged to supply fuel to a combustion device at a fuel flow rate FF, wherein the total fuel supply comprises a first fuel supply and a second fuel supply, the method comprising:

controlling a proportion P of a fuel flow rate FF supplied via a first fuel supply arrangement based at least in part on the fuel flow rate FF;

thereby, the metal temperature and/or emissions are improved.

The gas turbine, the load L, the fuel supply, the fuel flow rate FF, the combustion device, the first fuel supply, the second fuel supply, the controller and/or the proportion P may be as described with reference to the fifth aspect, the sixth aspect and/or the second aspect. For example, the emissions may be NOx emissions.

In one example, there is provided a method of controlling a gas turbine arranged to supply a load L, the gas turbine comprising a total fuel supply arranged to supply fuel to a combustion device at a fuel flow rate FF, wherein the total fuel supply comprises a first fuel supply and a second fuel supply, the method comprising:

thereby, the metal temperature and/or flame stability and/or emissions are improved.

In one example, the proportion P of the fuel flow rate FF supplied via the first fuel supply is controlled based at least in part on the reference fuel flow rate FFR.

In one example, the reference fuel flow rate FFR is at a first predetermined temperature T1 (preferably, the first predetermined temperature T1 is 323K) and/or a first predetermined load L1 (preferably, the first predetermined load L1 is 100%).

In one example, the proportion P of the fuel flow rate FF supplied via the first fuel supply is controlled based at least in part on a reference proportion PR of the fuel flow rate FF supplied via the first supply.

In one example, the reference proportion PR of the fuel flow rate FF supplied via the first fuel supply device is at a second predetermined temperature T2 (preferably, the second predetermined temperature T2 is 323K) and/or a second predetermined load L2 (preferably, the second predetermined load L2 is 100%).

In one example, a method comprises: controlling the proportion P of the fuel flow rate FF supplied via the first fuel supply based at least in part on a reference proportion split PRS of the fuel flow rate FF supplied via the first supply.

In one example, the reference proportional split PRS is a pilot percentage based on the turbine inlet temperature T1.

In one example, the reference proportional shunt PRS is based at least in part on a minimum fuel flow rate below which a liquid spray cone from a main fuel supply nozzle (e.g., a first fuel supply nozzle) collapses.

In one example, the reference proportional diversion PRS is based at least in part on a minimum fuel flow rate below which no positive and/or net flow enters the combustion device via a fuel supply nozzle (e.g., a first fuel supply nozzle).

In one example, the proportion P of the fuel flow rate FF supplied via the first fuel supply device is determined by P = (FFR · PR)/FF.

In one example, the method includes measuring an ambient temperature TA, and wherein the fuel flow rate FF is based at least in part on the ambient temperature TA.

In one example, the method includes measuring a combustion apparatus outlet temperature TX and/or a turbine inlet temperature T1, and wherein the proportion P of the fuel flow rate F supplied via the first fuel supply is controlled based at least in part on the fuel flow rate FF if the combustion apparatus outlet temperature TX is greater than a third predetermined temperature T3 and/or if the turbine inlet temperature T1 is greater than a fourth predetermined temperature T4.

In one example, if the burner outlet temperature TX is at most the third predetermined temperature T3, the proportion P of the fuel flow rate FF supplied via the first fuel supply is constant.

According to an eighth aspect, there is provided a tangible, non-transitory computer-readable storage medium having instructions recorded thereon, which, when executed by a controller for a gas turbine arranged to supply a load L, the gas turbine comprising a total fuel supply arranged to supply fuel to a combustion apparatus at a fuel flow rate FF, the total fuel supply comprising a first fuel supply and a second fuel supply, cause the controller to perform a method of controlling a gas turbine according to the seventh aspect and/or the third aspect.

Drawings

For a better understanding of the present invention, and to show how an exemplary embodiment thereof may be carried into effect, reference will now be made, by way of example only, to the accompanying drawings, in which:

FIG. 1 schematically depicts a longitudinal cross-section of a typical gas turbine;

FIG. 2A schematically depicts a longitudinal cross-section of a typical combustion apparatus, and FIG. 2B schematically depicts a cross-section along the line III-III in FIG. 2A;

FIG. 3 schematically depicts a block diagram illustrating obtaining a main fuel supply and a pilot fuel supply in a typical gas turbine having multiple combustion devices;

FIG. 4A shows a graph of turbine inlet temperature as a function of load for a typical gas turbine;

FIG. 4B illustrates a graph of turbine inlet temperature and pilot split as a function of load for a typical gas turbine;

FIG. 5 schematically depicts a controller for a gas turbine according to an exemplary embodiment;

FIG. 6 schematically depicts a gas turbine according to an exemplary embodiment;

FIG. 7 schematically depicts a method of controlling a gas turbine, according to an exemplary embodiment;

FIG. 8A illustrates a graph of turbine inlet temperature and combustion apparatus operating parameters according to an exemplary embodiment as a function of load for a gas turbine; and

FIG. 8B illustrates a graph of turbine inlet temperature and pilot split according to an exemplary embodiment as a function of load for a gas turbine.

Detailed Description

FIG. 5 schematically depicts a controller 50 for a gas turbine (not shown) according to an exemplary embodiment.

In more detail, the controller 50 is for a gas turbine arranged to supply a load L, the gas turbine comprising a total fuel supply arranged to supply fuel to the combustion device at a fuel flow rate FF, wherein the total fuel supply comprises a first fuel supply and a second fuel supply. The controller 50 is arranged to: one or more ratios R of the one or more burner operating parameters COP at the load L and the corresponding reference burner operating parameter coprr at the reference load LR are determined. The controller 50 is further arranged to: controlling the proportion P of the fuel flow rate FF supplied via the first fuel supply based at least in part on the determined one or more ratios R.

By controlling the proportion P (i.e., split) of the fuel flow rate FF supplied via the first fuel supply (e.g., pilot fuel supply) based at least in part on the determined one or more ratios R, the proportion P may vary along a Turndown Control Temperature (TCT) line (e.g., a substantially constant TCT line) as the load L varies (e.g., decreases from a full load L that may be provided by the gas turbine). In this manner, control of the gas turbine may be improved to improve flame stability and/or emissions, for example, as load L changes.

The controller may be arranged as previously described.

FIG. 6 schematically depicts a gas turbine 600 according to an exemplary embodiment.

In more detail, the gas turbine 600 is arranged to supply a load L. The gas turbine 600 comprises a total fuel supply 60, which total fuel supply 60 is arranged to supply fuel to the combustion means at a fuel flow rate FF, wherein the total fuel supply 60 comprises a first fuel supply 61 and a second fuel supply 62. The gas turbine 600 includes the controller 50 as described above with reference to FIG. 5. In particular, the controller 50 is arranged to determine one or more ratios R of one or more combustion device operating parameters COP at a load L and a corresponding reference combustion device operating parameter COPR at a reference load LR, respectively. The controller 50 is arranged to: the proportion P of the fuel flow rate FF supplied via the first fuel supply 61 is controlled based at least in part on the determined one or more ratios R.

FIG. 7 schematically depicts a method of controlling a gas turbine, according to an exemplary embodiment.

In more detail, the method is a method of controlling a gas turbine arranged to supply a load L, the gas turbine comprising a total fuel supply arranged to supply fuel to a combustion device at a fuel flow rate FF, wherein the total fuel supply comprises a first fuel supply and a second fuel supply.

In S701, one or more ratios R of one or more burner operating parameters COP at the load L to corresponding reference burner operating parameters coprr at the reference load LR are determined, respectively.

In S702, a proportion P of a fuel flow rate FF supplied via the first fuel supply is controlled based at least in part on the determined one or more ratios R, whereby flame stability and/or emissions are improved.

The method may comprise any of the steps previously described.

FIG. 8A illustrates a graph of turbine inlet temperature (TET) and combustion device operating parameters according to an exemplary embodiment as a function of load for a gas turbine.

Specifically, FIG. 8A illustrates a graph of the combustion intensity CI of the combustor, the equivalence ratio ER of the combustor, and the combustor inlet function CIF of the combustor as a function of load L, illustrating the behavior of these combustor operating parameters along the Turndown Control Temperature (TCT) line. As described above, the combustion intensity CI of the combustion apparatus, the equivalence ratio ER of the combustion apparatus, and the combustion apparatus inlet function CIF are determined according to equations 1 to 3. The combustion intensity CI of the burner, the equivalence ratio ER of the burner and the burner inlet function CIF are normalized to the full load L value (i.e. 100% load L). That is, the graph shows three ratios R of the three combustor operating parameters COP at the load L to the corresponding reference combustor operating parameter COPR at the reference load LR (i.e., 100% load L), respectively. When the TET is held constant along a constant TCT line, the operating parameters of these combustion devices are not constant.

In detail, the normalized combustion intensity CI of the combustion device decreases linearly as the load L increases along the TCT line, having a maximum value greater than unity (i.e. greater than at full load) at the low end of the constant TCT line and a minimum value at the high end of the constant TCT line. At a load L below the low end of the constant TCT line, the normalized combustion intensity CI of the combustion device decreases as TET decreases. At a load L above the high end of the constant TCT line, the normalized combustion intensity CI of the combustion device increases to full load L as TET increases.

In detail, the normalized equivalence ratio ER decreases linearly as the load L increases along the TCT line, the normalized equivalence ratio ER having a maximum value at the low end of the constant TCT line and a minimum value at the high end of the constant TCT line. At a constant load L below the low end of the TCT line, the normalized equivalence ratio ER decreases as TET decreases. At a constant load L above the high end of the TCT line, the normalized equivalence ratio ER increases to full load L as TET increases.

In detail, the normalized burner inlet function CIF increases linearly as the load L increases along the TCT line, the normalized burner inlet function CIF approaching a minimum at the low end of the constant TCT line and a maximum at the high end of the constant TCT line. At load L below the lower end of the constant TCT line, the normalized burner inlet function CIF decreases slightly as TET decreases. At a constant load L above the high end of the TCT line, the normalized equivalence ratio ER decreases slightly to full load L as TET increases.

FIG. 8B illustrates a graph of turbine inlet temperature (TET) and pilot split according to a load for a gas turbine according to an exemplary embodiment.

Specifically, fig. 8B shows a graph of a conventional pilot split (i.e., a proportion P of the fuel flow rate FF supplied via the first fuel supply means) according to a conventional pilot split map (solid line) compared with an exemplary pilot split (i.e., a proportion P of the fuel flow rate FF supplied via the first fuel supply means) according to an exemplary embodiment (dashed line).

In detail, as described above with reference to fig. 4B, as the load L decreases, the conventional pilot split is a predefined constant pilot split value along a constant TCT line.

Conversely, as the load L decreases, the exemplary pilot split value is non-constant along a constant TCT line, and as described above, the pilot split value is controlled based at least in part on the determined one or more ratios R.

In detail, the exemplary pilot split value increases linearly as the load L increases along the TCT line. At the low end of the constant TCT line, the exemplary pilot split value is less than the conventional pilot split, and at the high end of the constant TCT line, the exemplary pilot split value tends toward and/or is equal to the conventional pilot split. At load L below the low end of the constant TCT line, the exemplary pilot split value increases as TET decreases, is less than the conventional pilot split, but tends toward the conventional pilot split as load L decreases. At a load L above the high end of the constant TCT line, the exemplary pilot split value decreases as TET increases until a full load L, substantially equal to the conventional pilot split value. That is, for a given load L, the exemplary pilot split value is at most a conventional pilot split value, and for an intermediate load L (e.g., in the range of about 10% to 60% of full load), the proportion P may be less than the conventional pilot split value.

As described above, for example, controlling the proportion P in this manner can be applied as a modification to a conventional pilot fuel control algorithm to calculate a pilot split offset for each load L based at least in part on the determined one or more ratios R, and to apply the pilot split offset to a conventional pilot split map and/or to envelope the map.

While preferred embodiments have been shown and described, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the scope of the invention as defined in the following claims and as described above.

Note all files and documents below: documents and documents which are filed concurrently with or previous to this specification in connection with this specification and which are to be viewed by the public in connection with this specification are hereby incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims and drawings) and/or all of the steps of any method or process so disclosed in the above-described form may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed in the above-mentioned form.

Claims

1. A controller for a gas turbine arranged to supply a load L, said gas turbine comprising a total fuel supply arranged to supply fuel to a combustion device at a fuel flow rate FF, wherein said total fuel supply comprises a first fuel supply and a second fuel supply, wherein said controller is arranged to:

determining one or more ratios R of one or more burner operating parameters COP at said load L and of a corresponding reference burner operating parameter COPR at a reference load LR, respectively; and is provided with

Controlling a proportion P of the fuel flow rate FF supplied via the first fuel supply based at least in part on the determined one or more ratios R,

wherein the burner operating parameter COP is a burner operating parameter COP selected from the group consisting of a combustion intensity CI of the burner, an equivalence ratio ER of the burner and a burner inlet function CIF of the burner.

2. A gas turbine arranged to supply a load L, the gas turbine comprising a controller according to claim 1.

3. A method of controlling a gas turbine arranged to supply a load L, said gas turbine comprising a total fuel supply arranged to supply fuel to a combustion device at a fuel flow rate FF, wherein said total fuel supply comprises a first fuel supply and a second fuel supply, said method comprising:

determining one or more ratios R of one or more combustion device operating parameters COP at said load L to corresponding reference combustion device operating parameters COPR at a reference load LR, respectively; and

controlling a proportion P of the fuel flow rate FF supplied via the first fuel supply based at least in part on the determined one or more ratios R;

thereby, flame stability and/or emissions are improved,

4. The method of claim 3, wherein the combustion intensity CI is determined based at least in part on a heat input HI for the gas turbine, a compressor outlet pressure CEP of the gas turbine, and/or a combustion device volume CV of the combustion device, and wherein the method comprises:

determining the combustion intensity CI;

determining a first ratio R1 of the combustion intensity CI at the load L to a reference combustion intensity CIR at the reference load LR; and

controlling the proportion P of the fuel flow rate FF supplied via the first fuel supply based at least in part on the determined first proportion R1.

5. The method of claim 4, wherein the combustion intensity CI is determined by CI = HI/(CEP x CV), and wherein the method comprises: the heat input HI, the compressor outlet pressure CEP and/or the combustion device volume CV are determined.

6. The method of any of claims 3 to 5, wherein the equivalence ratio ER is determined based at least in part on the fuel flow rate FF for the combustion device, an air flow rate FA for the combustion device, and/or a stoichiometric fuel-air ratio SFAR, and wherein the method comprises:

determining the equivalence ratio ER;

determining a second ratio R2 of the equivalence ratio ER at the load L to a reference equivalence ratio ERR at the reference load LR; and

controlling the proportion P of the fuel flow rate FF supplied via the first fuel supply based at least in part on the determined second ratio R2.

7. The method of claim 6, wherein the equivalence ratio, ER, is determined by ER = (FF/FA)/SFAR, and wherein the method comprises: determining the fuel flow rate FF, the air flow rate FA, and/or the stoichiometric fuel-to-air ratio SFAR.

8. The method according to any of claims 3-5 and 7, wherein the combustion device inlet function, CIF, is determined based at least in part on an air flow rate, FA, for the combustion device, a compressor outlet temperature, CET, of the gas turbine, and/or a compressor outlet pressure, CEP, of the gas turbine, and wherein the method comprises: determining the combustion device inlet function CIF;

determining a third ratio R3 of the combustion device inlet function CIF at the load L to a reference combustion device inlet function CIFR at the reference load LR; and

controlling the proportion P of the fuel flow rate FF supplied via the first fuel supply based at least in part on the determined third ratio R3.

9. The method of claim 8, wherein the combustion device inlet function, CIF, is determined by CIF = (FA × √ CET)/CEP, and wherein the method comprises: determining the air flow rate FA, the compressor outlet temperature CET and/or the compressor outlet pressure CEP.

10. The method of any one of claims 3-5, 7, and 9, the method comprising:

determining an exhaust flow rate FB; and

controlling the proportion P of the fuel flow rate FF supplied via the first fuel supply based at least in part on the determined bleed flow rate FB.

11. The method according to any one of claims 3-5, 7 and 9, wherein said load L and/or said fuel flow rate FF and/or turbine inlet temperature TET are substantially constant.

12. The method according to any one of claims 3-5, 7 and 9, wherein the reference load LR is the full load that can be supplied by the gas turbine.

13. The method of any of claims 3-5, 7 and 9, wherein said first fuel supply is a pilot fuel supply.

14. A tangible non-transitory computer readable storage medium having instructions recorded thereon, which when executed by a controller for a gas turbine arranged to supply a load L, the gas turbine comprising a total fuel supply arranged to supply fuel to a combustion device at a fuel flow rate FF, wherein the total fuel supply comprises a first fuel supply and a second fuel supply, cause the controller to perform a method of controlling a gas turbine according to any one of claims 3 to 13.